Keyframe side pin guides of musical instrument



Jan. 16, 1968 YOSHIYUKI MATSUMOTO 3,363,499

KEYFRAME SIDE PIN GUIDES OF MUSICAL INSTRUMENT Filed Dec. 8, 1966 2Sheets-Sheet 1 F I G. l

e LEFT RIGHT l5 .6 2w 18 BACK W A #4 l9 FRONT/,

F l G. 2(b) Ilia 111:1?

United States Patent 3,363,499 KEYFRAME SIDE PIN GUIDES 0F MUSICALINSTRUMENT Yoshiynki Matsumoto, Harnamatsu-shi, Japan, assignor toNippon Gakki Scizo Kabushiki Kaisha, Hamamatsushi, Japan Filed Dec. 8,1966, Ser. No. 600,118 Claims priority, application Japan, Dec. 17,1965, 40/ 102,97 0 4 Claims. (Cl. 84--432) This invention relates topianos and like musical instruments and more particularly to new andimproved keyframe side pin guides whereby warp curving of the front partof a keyframe can be prevented,

Keyframe side pin guides known heretofore have been incapable ofpreventing upward warp curving of the front member of the keyframe asdescribed more fully hereinafter.

It is an object of the present invention to provide keyframe side pinguides of relatively simple construction and arrangement whereby upwardwarp curving of the front member of the keyframe can be prevented.

Briefly stated, the present invention provides keyframe side pin guidesfor keyframes of pianos and like musical instruments, each of the sidepin guides comprising a combination of a side pin guide body havinghorizontal slot holes for mounting of the guide body onto a key block, avertical cutout slot for receiving of the keyframe side pins, and atapped hole coaxially aligned with and disposed above the cutout slot, aguide piece adapted to fit in and slide along the cutout slot above andin contact with a pin fitted in the cutout slot, and an adjusting screwscrewed in the tapped hole to press the guide piece firmly against theside pin and thereby to prevent upward curving of the front member ofthe keyframe.

The nature, principle, and details of the invention will be more clearlyapparent from the following detailed description when read inconjunction with the accompanying drawings, in which like parts aredesignated by like reference numerals.

In the drawings:

FIG. 1 is a perspective view showing one example of the keyframe and keyblocks of a grand piano;

FIGS. 2(a) and 2(b) are fragmentary perspective views showing inenlargement the part Ila of FIG. 1 of one part of a keyframe and akeyframe side pin guide of known type;

FIGS. 3(a) and 3(b) are fragmentary perspective views similar to FIGS.2(a) and 2(b) showing one example of application of the keyframe sidepin guide according to the invention;

FIG. 4- is an elevational view indicating the relationship between akeyframe side pin guide and side pin of known type;

FIG. 5 is an elevational view indicating the relationship between apreferred embodiment of the keyframe side pin guide and pin according tothe invention;

FIG. 6 is an elevational view showing the assembled state of the sidepin guide shown in FIG. 5;

FIGS. 7(a), 7(b), and 7(0) are respectively an elevational frontal View,a side elevational view, and a bottom View of the side pin guide bodyconstituting the stationary structure of the side pin guide shown inFIGS. 5 and 6.

FIG. 7(d) is a fragmentary sectional view taken along the planeindicated by line VIIdVIId of FIG. 7(0) in the direction indicated; and

FIGS. 8(a) and 8(1)) are respectively side elevational and plan viewsshowing the guide piece of the side pin guide shown in FIGS. 5 and 6.

Throughout the following disclosure, directions referred to as front,back, left, right, above, be-

low, etc., are those of the musical instrument, i.e., a grand piano inthe example herein set forth.

In general, the keyframe of a grand piano, as shown in FIGS. 1, 2(a),and 2(b), is formed by the assemblage of a front rail 3, a balance (orintermediate) rail 14, a back (or rear) rail 15, and transverse slats16, 17a, 18, and 19 and is free to move horizontally left and right overa key bed (not shown) under the guidance of back rail guides 1, keyframeside pin guides 5 and side pins 2 engaged with the side pin guides 5.The side pin guides 5 are respectively mounted by wood screws 6 onto akey block 4 at the bass end and a key block 4a at the treble end and areso constructed and arranged as to slow the horizontal movement of thekeyframe. The side pin guides 5 function to engage with and guide pins 2partly imbedded fixedly in the left and right ends of the front part ofthe keyframe and extending outwardly toward the left and right.

For these side pin guides, pin guides each as illustrated in FIG. 4 haveheretofore been used to engage with pins 2 as indicated. Each of theseknown pin guides 5 is pr0- vided with horizontal slots 3 for insertiontherethrough of wood screws 6 for fine adjustments front-and-back andupand-down of the mounted position of the pin guide structure 5. Acentral vertical slot 24 is also provided for receiving and engagingwith a side pin 2.

When these known side pin guides 5 are mounted on the key blocks 4 and4a respectively at the bass and treble ends and the side pins 2 areengaged with the slots 24, the engagement relationship between a sidepin 2 and its respective slot 24 is frequently such that a gap 7 remainsabove the pin 2, although the engagement is tight with respect to thefront-and-back direction, because of deviations in the imbeddedpositions of pins 2 in the ends of the front rail 3 of the keyframe.

For this reason, when the front rail 3 of the keyframes assumes acurvature due to warping after a long period of use, it is not possibleto prevent this warping. Moreover, in many cases it is not possible toeliminate this space 7 to cause the pin 2 to contact the upper end ofthe slot 24 even by adjustment of the aforementioned fineadjustment woodscrews 6.

The reason for this is that there are certain limits to the adjustmentof the position of the side pin guide 5 in the up-and-down direction bymeans of the adjusting wood screws 6, these upward and downward limitsbeing at the extremities of a range of movement which is /2 of thedifference between the diameter of the wood screws 6 and the width ofthe slots 8 into which the screws are inserted, and, moreover, there isthe possibility of the side pin guide 5 shifting its position, when thescrews 6 are loosened to replace the guide 5 in the correct position andthen retightened. The width of the slots 8 cannot, of course, beenlarged beyond a certain limit imposed by the necessity of the heads ofthe screws 6 to be engaged with the guide structure 5 and by the limitto the strength of the guide structure itself.

The present invention contemplates overcoming the above describeddifiiculties by providing a side pin guide of new and improvedconstruction and arrangement as described hereinbelow with respect to apreferred embodiment of the invention.

Referring to FIGS. 3(a), 3(b) and 5, the example of the side pin guideaccording to the invention comprises a pin guide body 10 of symmetricalsaddle shape and integral structure having two flange parts 1% joined byan upper cross piece or bridge 10a, an adjusting screw in screw threadengagement with a vertical tapped through hole in the bridge 10a, and aguide piece 11 slida'bly engaged in a vertical cutout slot 21 in theguide body 10 below the bridge 10a and between the inner sides of theflange parts 10b. The flange parts 10b are provided respectively withhorizontal slot holes 17 for mounting the guide body onto a key block.

The adjusting screw 9 is inserted from the upper side of the bridge a,and the lower tip of the screw 9 rests against the upper surface of theguide piece 11. The guide piece 11 has a curved lower surface forcontacting a side pin 2 of the keyframe, which side pin 2, in assembledstate, is engaged in the cutout slot 21 below and against the guidepiece 11.

FIGS. 6, 7(a), 7(b), 7(c), 7(d), 8(a), and 8(b) show the details of theside pin guide assembly and disassembled guide body 10 and guide piece11. The guide body 10 is provided on its rear surface to contact the keyblock with numerous projections 10d for secure fastening against the keyblock without slippage therebetween. The flange parts 10b at their partson the sides of the slot 21 have inwardly projecting flanges 10e betweenwhich the guide piece 11 is slidable in vertical direction. Each flange10a has near its lower end a stop 100 for preventing the guide piecefrom slipping out after assembly.

The guide piece 11. in plan view has an H-shaped cross section withguide flanges 11b for slidable contact with the inside faces of theflanges 10s of the guide body 10 and is provided with ridges 11a forproviding sliding friction on its surfaces to contact the opposedsurfaces of the flanges 10e. As mentioned briefly hereinabove, the guidepiece 11 has a curved lower surface. The curvature is a single convexcurvature whose generatrix direction is perpendicular to the axis of theside pin 2 to contact the surface.

The guide body 10 and the guide piece 11 are made of self-lubricativematerial such as a polyacetal resin which is well known, for example,under the trade name of Delrin (produced by Du Pont) or Duracon(produced by Daini-hon Celluloid K.K., Japan), each being the syntheticresin of 100% polyacetal containing small amount of impuritiessometimes.

The key blocks 4 and 4a at the bass and treble ends are secured to thekey bed (not shown). Each side pin guide assembly is mounted on itsrespective key block by means of wood screws 12 with washers 13, thescrews being passed through the slot holes 17 of the guide body 10 andscrewed into the key block as shown in FIG. 3(a).

The surface of each key block for mounting of the side pin guide isrecessed so that, when the side pin guide is mounted, its outermost partdoes not project outward beyond the surface of the key block facing thekey (not shown). Furthermore, a groove or cutout 20 is provided in thekey block above the adjusting screw 9 so that a screwdriver can beinserted from above to turn the adjusting screw 9.

In assembled state, each side pin 2. imbedded at its root end in thekeyframe front rail 3 is fitted at its other end into the slot 21 of theside pin guide as indicated in FIG. 5. There are some deviations in theimbedded positions of the side pins 2. A front-and-back deviation of theimbedded position of each side pin 2 is compensated for by the initialmounting position of the corresponding side pin guide. A deviation ofthe imbedded position in the vertical direction can be readilycompensated for, and the guide piece 11 caused to closely contact theupper side of the pin 2, by causing the guide piece 11 to slide alongthe slot 21 by means of the adjusting screw 9 without the necessity ofmaking adjustments 'by means of the mounting screws 12 as in the priorart.

By the above described construction and arrangement of the side pinguide, the side pin 2 can be closely held by the guide piece 11 withoutexcessive force. Accordingly, the keyframe front rail 3 is preventedfrom curving upward. For this reason, there is no spoilage of the touch,and the keyframe can be constantly maintained in its normal state.

Since the pin guide body 10 and the guide piece 11 are made of aself-lubricative material such as, for example, a polyacetal resin,sliding movements of the side pin 2. in contact with the guide body 10and guide piece 11 do not produce noise.

It should be understood, of course, that the foregoing disclosurerelates to only a preferred embodiment of the invention and that it isintended to cover all changes and modifications of the example of theinvention herein chosen for the purposes of the disclosure, which do notconstitute departures from the spirit and scope of the invention as setforth in the appended claims.

What I claim is:

1. In a piano or like musical instrument, keyframe side pin guides eachcomprising: a side pin guide body having slot holes for mounting of saidbody onto a key block, a cutout slot, and a tapped hole; a guide pieceadapted to fit in and slide along said cutout slot; and an adjustingscrew thread-engaged in said tapped hole to press said guide pieceagainst a side pin imbeddedly fixed to a keyframe front member.

2. In a piano or like musical instrument having a keyframe with sidepins imbedded in the keyframe front member, keyframe side pin guideseach comprising, in combination: a side pin guide body having horizontalslot holes for mounting of said body onto a key block, a vertical cutoutslot for receiving one of said side pins, and a tapped hole coaxiallyaligned with and disposed above said cutout slot; a guide piece adaptedto fit in and slide along said cutout slot above and in contact withsaid side pin; an adjusting screw thread-engaged in said tapped hole topress said guide piece against said side pin; and fastening means passedthrough said slot holes for mounting said side pin guide body onto thekey block adjustably in a horizontal direction.

3. The keyframe side pin guides as claimed in claim 2 in which the sidepin guide body and the guide piece are made of -a self-lubricativematerial.

4. The keyframe side pin guides as claimed in claim 3 in whichpolyacetal is used as the self-lubricative material.

References Cited UNITED STATES PATENTS 745,509 12/1903 Muller 84-4321,699,465 1/1929 Edward 84-432 RICHARD B. WILKINSON, Primary Examiner.

CHARLES OVERBEY, Assistant Examiner.

1. IN A PIANO OR LIKE MUSICAL INSTRUMENT, KEYFRAME SIDE PIN GUIDES EACHCOMPRISING: A SIDE PIN GUIDE BODY HAVING SLOT HOLES FOR MOUNTING OF SAIDBODY ONTO A KEY BLOCK, A CUTOUT SLOT, AND A TAPPED HOLE; A GUIDE PIECEADAPTED TO FIT IN AND SLIDE ALONG SAID CUTOUT SLOT; AND AN